1. Field of the Invention
The present invention relates to an apparatus for positioning a work implement in predetermined operative attitudes and more particularly to a remotely controllable actuator which has utility when employed to position variously designed spool valve assemblies of a hydraulic valve in selected operative positions relative to a predetermined path of travel thereby permitting the selective release of a source of fluid under pressure to accomPlish assorted tasks, the actuator imparting improved performance characteristic to a hydraulic valve which is so actuated.
2. Description of the Prior Art
The beneficial effects of employing remotely controllable devices for the performance of assorted tasks have been known for some time. Such devices, heretofore, typically have been utilized to perform various dangerous or undesirable operations. More recently, research has been conducted on the remote actuation of assorted valve assemblies such as those valve assemblies utilized to control the selective release of hydraulic fluid under pressure. Heretofore, the remote metering of various fluids have been accomplished by assorted solenoid valve assemblies. Such a remotely controllable solenoid valve assembly is disclosed in U.S. Pat. No. 4,610,267 to Beck et al. and which relates to a fast response solenoid valve assembly. While remotely controllable valves of various designs have operated with varying degrees of success, they commonly possess shortcomings which have detracted from their usefulness. For example, prior art remote control actuators have not been capable of providing accurate control of the force applied to a valve spool nor accurate control of the rate of movement of the valve spool.
While the prior art is replete with numerous examples of remotely controllable devices which have been developed for particular applications and environments, they each suffer, however, from readily apparent drawbacks which have detracted from their utilization except in combination with particular devices. For example, such devices have typically been quite cumbersome to utilize or alternatively have had physical dimensions which impead the utilization of the apparatus so equipped. Further, manufacturers who produce remotely controllable devices for various machines must, as a general matter, manufacture assorted differently designed parts in order to assemble these individual devices, with the costs attendant to such design and manufacture. Moreover, these various devices have individually unique maintenance and supply problems which are peculiar to the individual devices under consideration.
Still another significant problem with the prior art devices and practices results from characteristics inherent in their individual designs. For example, where conversion or retrofit is required with such devices, they must either be converted at a remote field location or returned to a manufacturer for such conversion. Neither approach has proven satisfactory, in the first instance because of lack of reliability when installed at remote field locations, and in the second instance, because of the expenses attendant to returning such devices to the manufacturer. In addition, the initial cost of manufacturing and installing the device, as well as the overall maintenance cost requirements related to these devices may be substantial in some instances.
Therefore, it has long been known that it would be desirable to have a remotely operable actuator for positioning a work implement and which has particular utility when utilized to position a conventionally designed spool valve assembly, the apparatus operable to position the spool valve assembly precisely and with a high degree of reliability, the apparatus being of compact configuration and remotely operable to actuate the spool valve assembly of assorted differently designed devices with the attendant benefits to be derived from such remote operation.